The present invention relates to the field of agricultural equipment for harvesting crops. More particularly, the invention relates to a detector for sensing rocks and other dense objects which could damage cutter knives and other internal equipment components.
Many different types of farm equipment harvest crops and other plant materials for human and animal consumption. Grain combines for wheat, corn, soybeans, milo and other crops separate the grains from the stalks. Hay bines and silage cutters collect the plant stalks for animal feed. Other agricultural equipment includes disc bines, swathers, and other devices for collecting crops and plant materials.
Wire, metal trash, and rocks are commonly found in cultivated fields. Metal trash enters the fields from adjacent roads, hydrocarbon producing wells, and other trash sources. When such foreign objects enter the harvesting equipment, the objects frequently damage internal components such as teeth, cutter knives, and other crop handling equipment. Although grain harvesters such as combines typically receive the foliage intake above the ground elevation, harvesters such as silage cutters gather foliage near the ground elevation and are particularly susceptible to the entry of foreign materials. Silage cutters chop the plant material into small lengths which are collected and stored in a dirt pit or silo. Fermentation of the plant material prevents decay and converts the plant material into a silage material easily digested by livestock during winter months.
When a rock contacts the cutter knives in a silage cutter, the knives shatter or end, requiring replacement of the damaged knives. This damage is costly because of the equipment cost, labor to replace the knives, and lost production time. Lost production time is particularly important for custom harvesters operating twenty four hours per day during brief harvest periods.
Harvester equipment requires careful design because of the multiple field variables in collecting crops and other plant materials. If a screen or filter is placed to guard against undesirable debris, the plant material can collect against the screen or filter and ultimately clog the equipment. The structure and composition of undesirable debris also varies from rocks, to irregularly shaped tree branches, to man-made refuse. These variables complicate any system which seeks to maximize plant material collection.
Harvester equipment typically incorporate pressure equipment which prevents oversupply of plant material into the feed rolls. The pressure equipment routinely adjusts the feed roll pressure in response to variations in the plant material intake. As the harvester moves through a field or turns at the end of a pass, normal variations in the plant material density and in the equipment cutting swath changes the plant material quantity entering the feed rolls. When too much plant material enters the feed rolls and threatens to clog the equipment, a load detector reverses the feed rolls. Equipment operation can continue at a rate consistent with the load capabilities of the equipment.
Modern harvesters also incorporate metal detectors for sensing the intrusion of metal objects into the feed, drive rolls. The metal detectors typically use a magnetic field which is interrupted by the passage of metal. Such passage triggers an alarm and automatically pulls the drive rolls out of gear to prevent further movement of the metal toward delicate cutter knives. Typically, the metal is removed from the feed rolls by reversing the drive rolls.
U.S. Pat. No. 4,496,105 to Fleming et al. (1985) disclosed a forage harverter drive and electric control having an overload sensitive switch. In U.S. Pat. No. 5,070,682 to Bohman (1991), a microphone detected the presence of hard objects on a feed mechanism. When a hard object was detected, such object was already located within the feed mechanism and was in position to damage equipment. U.S. Pat. No. 4,768,525 to Tanis (1988) disclosed a sensing mechanism which detected the noise made by a stone after the stone entered the machine and was in contact with the components. Both of this concepts used noise detecting devices to distinguish the sound made by stones in contact with the machinery.
Except for these noise detection devices, most harvester equipment does not detect the presence of nonmetallic foreign objects in the plant material. Nonmetallic foreign objects are not detected by the metal detectors and may be sufficiently small to pass with the plant material through the initial feed rolls. Because of the frequency of rocks in certain cultivated fields, operators typically raise the intake elevation to reduce rock intake into the harvester equipment. This reduces the cutting efficiency of the equipment because more of the plant material is left unharvested. The problems of harvesting certain fields is particularly difficult for custom harvest crews which migrate from one geographic area to another with the change in harvest season. Because such crews are not knowledgable regarding the conditions of each field, and because such crews economically depend upon continuous operation, nonmetallic debris creates a special threat to custom cutting operations.
There is, accordingly, a need for an apparatus capable of detecting nonmetallic debris before such debris contacts internal harvester components. Such apparatus must be portable and should be adaptable to conventional harvester equipment.
The present invention provides an apparatus for detecting nonmetallic debris in plant material gathered by a harvester. The apparatus comprises a housing attachable to the harvester, a signal generator engaged with the housing for transmitting a signal capable of distinguishing the nonmetallic debris from the plant material, a sensor for receiving the generator signal and for producing an alarm signal when nonmetallic debris in the plant material is distinguished, and a controller for receiving the alarm signal and for modifying operation of the harvester in response to the alarm signal.
Different signals can identify the nonmetallic debris. The signal generator and sensor can function based on energy from laser light waves, from sound waves, microwave, gamma, x-ray, fluoroscope, or other energy forms.
The invention also discloses a plant material harvester for detecting nonmetallic debris in the plant material. The harvester comprises harvester equipment which is mobile relative to the plant material, plant material collecting equipment attached to the harvester equipment for gathering the plant material, a signal generator engaged with the harvester equipment for transmitting an energy wave signal capable of distinguishing the nonmetallic debris from the plant material, a sensor for receiving the generator signal and for producing an alarm signal when the energy wave signal distinguishes nonmetallic debris in the plant material, and a controller engaged with the harvester equipment for receiving the alarm signal and for modifying operation of the harvester equipment in response to the alarm signal.